Human discourse about pathogens tends to be pretty narrowly focused on those viruses and organisms that directly infect humans. This is, I think, entirely understandable. Our health is hugely important to every aspect of our lives, as we all become aware when we get sick, or develop chronic health problems. I know nobody reading this has any personal experience with this, but if you add in something like an epidemic that goes global, well that adds a whole other layer to it. We have ample reason to be somewhat obsessed with our health and things that affect it.

Second to that, we care about the health of our food and our working and companion animals, which I would argue is also mostly about our own health.

Less attention is given to how pathogens affect wildlife. We tend to view nature as something that takes care of itself, when we’re not actively destroying it, but of course other life forms have all the same health concerns we do, adjusted for the specifics of their species. More than that, humans have acted as something akin to global plague rats, as we’ve scurried about all over the surface of this planet, introducing animals, plants, and microorganisms everywhere we go. Well, now we’ve found a new way to introduce microbes are new to our ecosystems, this time because of their age.

We’ve seen it in science fiction and horror, folks, and now it’s time for the real life version. Are you prepared for a panoply of prehistoric pathogens?

The idea that “time-traveling” pathogens trapped in ice or hidden in remote laboratory facilities could break free to cause catastrophic outbreaks has inspired generations of novelists and screenwriters. While melting glaciers and permafrost are giving many types of dormant microbes the opportunity to re-emerge, the potential threats to human health and the environment posed by these microbes have been difficult to estimate.

In a new study, Strona’s team quantified the ecological risks posed by these microbes using computer simulations. The researchers performed artificial evolution experiments where digital virus-like pathogens from the past invade communities of bacteria-like hosts. They compared the effects of invading pathogens on the diversity of host bacteria to diversity in control communities where no invasion occurred.

The team found that in their simulations, the ancient invading pathogens could often survive and evolve in the modern community, and about 3 percent became dominant. While most of the dominant invaders had little effect on the composition of the larger community, about 1 percent of the invaders yielded unpredictable results. Some caused up to one third of the host species to die out, while others increased diversity by up to 12 percent compared to the control simulations.

The risks posed by this 1 percent of released pathogens may seem small, but given the sheer number of ancient microbes regularly released into modern communities, outbreak events still represent a substantial hazard. The new findings suggest that the risks posed by time-traveling pathogens — so far confined to science fiction stories — could in fact be powerful drivers of ecological change and threats to human health.

I tend to have mixed feelings about this kind of simulation research, but there is no question that there are viruses, bacteria, and even roundworms that were frozen tens of thousands of years ago (or thousands of thousands, in the case of that bacterium), and that are viable once thawed. While it’s certainly possible some of them could directly infect humans, it’s far more likely that the danger from these ancient microbes lies in their potential to further disrupt ecosystems that are already collapsing under the weight of habitat destruction, pollution, and global warming.

Some of you may recall that I posted last year about the way European earthworms have been colonizing and altering North American ecosystems for centuries, to the point where most folks in the US have never seen an indigenous earthworm. More recently, there was that research indicating that invasive species cause more economic damage than earthquakes, so you can see why some people might have fears about ancient frozen bugs that have absolutely nothing to do with worrying about the next pandemic.

As I so often say, humans are part of the ecosystems that surround us, and we ignore that fact at our peril. The physical changes that we’ve caused on the surface of our planet are devastating, and they’re more than enough to cause a mass extinction all by themselves. Add in prehistoric organisms, which could end up altering the climate themselves, and it’s hard to tell what could happen. Unfortunately, it’s also very easy to look at all of this and feel some level of despair. I do get that, and of course I feel it myself sometimes, but I continue to believe that we have the means to survive this crisis, as a species. That window of opportunity is closing, but it’s never over till it’s over, and the more we understand about what’s happening, the better our chances of finding a way through.

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